The present invention relates to infrared furnaces and more particularly to devices for mounting infrared lamps in the heating chamber of such a furnace.
An infrared furnace provided with an endless conveyor belt is highly useful since transversely disposed infrared lamps located at different zones along the length of the heating chamber of the furnace can be quickly heated up as needed to give desired temperature profile in the direction of travel of the conveyor belt.
An infrared furnace of this type that is particularly advantageous comprises an elongated heating chamber having a rectangular cross section with its walls constructed of compressed, high temperature, porous insulation. A thin sheet metal housing or casing is provided to structurally hold the walls of the insulation together. Within the heating chamber, a first series of transversely disposed infrared lamps is provided above the conveyor belt and a second series of transversely disposed infrared lamps is provided below the conveyor belt. Plenum chambers on the top and bottom of the heating chamber enable a pressurized cover gas to slowly filter through the upper and lower walls of porous insulation material into the interior of the heating chamber. Such an infrared furnace is disclosed in a copending patent application of N. Robert Crain et al, Ser. No. 119,496, filed Feb. 7, 1980.
In such an infrared furnace, it is desirable to provide for mounting the infrared lamps so that the metal terminals on the ends of the quartz tube thereof protrude outside the sidewalls of the heating chamber so that they can be cooled by cooling air. It should be appreciated that inasmuch as a plurality of infrared lamps are used in such a heating chamber, a large number of pairs of mounting devices are provided on the sidewalls thereof. Thus, it is desirable to provide for the end portions of the infrared lamps to be held in the mounting devices in a substantially gastight manner so that air or any other gases will not readily seep into or out of the heating chamber at these points. Still further, it is highly desirable to mount the infrared lamps on the sidewalls of the heating chamber so that each can be individually readily replaced in the event it burns out.